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Old 04-06-2012, 11:05 AM
Loman Loman is offline
Join Date: Feb 2008
Location: Dublin, Ireland
Posts: 163
Default MGL AP pitch servo pushrod geometry

MGL don't give specific instructions on the mechanical mounting of their AP servos (just the location of the mounting holes on the body) so I followed the Trutrak documentation for inspiration, as their servo motor appears to be physically identical to the MGL (and Dynon). I made a mount for the pitch servo that follows their pattern and I am happy with it. Now I am moving on to the pushrod.

Trutrak say to drill the bell crank 2.5 inches from the pivot in order to mount the pushrod. The arm on the servo however is only 1.5" from pivot to mounting hole. Surely, this introduces an element of gearing so that x degrees of rotation at the servo will give something other than x degrees rotation at the bell crank.

Does this even matter? Would I not be better having the same radius from pivot to pushrod mount at both ends?
Loman O'Byrne
RV9 TU. O-320-E2D. Engine hung, working on panel, Arklow, Ireland
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Old 03-14-2013, 11:03 AM
Bob Ellis's Avatar
Bob Ellis Bob Ellis is offline
Join Date: Jul 2007
Location: Pembrokeshire, UK
Posts: 224

Would I not be better having the same radius from pivot to pushrod mount at both ends?
Posted reply for future searchers .....

This is what Trio instructs you to do when installing their Gold Servos (the only option available to me when I built my 8 with a MGL Voyager G2). This geometry works well for my set up and am very pleased with the MGL autopilot and its capabilities.
Bob Ellis
G-JBTR Having a ball flying this wonderful machine
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